Metagenomic analysis of Pigs' faecal microbiome and its functional response associated with dietary fibre

Abstract

Pig husbandry is the most valued and economically sustainable husbandry in the livestock farming system. The performance and productivity of the pig are chiefly dependent on the nutritional factor steered by gut beneficial bacteria. The swine gut microbiome has a direct relationship with feed efficiency. As a consequence, identifying microbial taxonomy and functional capacity is critical for proper nutrient digestion. In the present investigation, eighteen grower pigs aged 3 months and weighing 30{+/-}0.55 kg were allocated into three different groups using a randomized block layout and supplemented with QPM maize fodder of 0, 5, and 10% to the basal diet by substituting (wt/wt on DM) the maize grains, and named as T0, T1, and T2 to probe the increase in gut beneficial bacteria found in the faecal contents. For comparison with T0, T1, and T2, a random faecal sample designated R was collected from six grower pigs of the same age group and bodyweight fed a maize-soya bean-based diet. The experiment is being carried out to investigate the effect of various maize fodder levels on the metagenomic profiles of pig gut microbiota using the 16S rRNA gene. All of the experimental diets were iso-nitrogenous, with protein content ranging from 18.37 to 18.63 per cent. The data generated by 16S rRNA amplicon analysis was 68, 56, 61, and 39 Mb in R, T0, T1, and T2 samples, respectively. From taxonomic distribution, bacterial phyla namely Firmicutes, Bacteroidetes, Proteobacteria, and Spirochetes are found in descending order of relative abundance in the R, T0, and T1 groups, respectively, while Spirochaetes, Proteobacteria, Fibrobacteres, Bacteroidetes, and Firmicutesare found in descending order of relative abundance in the T2 group. The relative profusion of Fibrobacter succinogenes is 0.89% and 16.84% in the T1 and T2 groups. According to the findings, a higher level of maize fodder in the diet of grower pigs promotes the growth of fibre-degrading bacteria in the gut microbiota, particularly Fibrobacter succinogenes. Moreover, feeding green maize has decreased the population of methanobacteria in the gut of pigs, which in turn has limited the production of methane.